Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for performing backoff in a wireless communication system.
Related Art
Universal mobile telecommunications system (UMTS) is a 3rd generation (3G) asynchronous mobile communication system operating in wideband code division multiple access (WCDMA) based on European systems, global system for mobile communications (GSM) and general packet radio services (GPRS). The long-term evolution (LTE) of UMTS is under discussion by the 3rd generation partnership project (3GPP) that standardized UMTS.
Random access procedure in which a network for the first time knows that some user equipments (UEs) are trying to get access may be performed in 3GPP LTE. At this stage, the UE does not have any resource or channel available to inform the network about its desire to connect to it, so it will transmit its request over the shared medium. Now there are two possibilities at this stage, either there are many other UEs in the same area (same cell) transmitting same request in which there is also a possibility of collision among the requests coming from various other UEs. Such random access procedure is called contention based random access procedure. In second scenario, the network can inform the UE to use some unique identity to prevent its request from colliding with requests coming from other UEs. The second scenario is called contention free or non-contention based random access procedure.
Meanwhile, backoff may be performed for the random access procedure. Backoff means that transmission of a random access preamble is delayed if a random access response reception and/or contention resolution in the random access procedure is considered not successful.
A method for performing backoff efficiently may be required.